This invention relates to article tagging and more particularly is concerned with applying tags to articles whereby their presence can be detected by electronic article surveillance techniques.
It is known for retail stores to provide certain of their articles for sale with tags formed of electromagnetic sensor material which can be detected by detection equipment. Ordinarily, at the point of sale, the cashier removes the tag from the article. Alternatively, the cashier deactivates the tag or by-passes the detection equipment. If, however, a thief attempts to avoid the cashier with the intention of stealing the article, he must necessarily pass the detection equipment which detects the presence of the tag and sounds an alarm. Hitherto, the tags have generally been applied, at the store, either manually or using a hand operated applicator of the type used to apply pressure sensitive adhesive labels. Such applicators are used in conjunction with a carrier tape in the form of a siliconised release paper or liner carrying detectable devices which are transferred from the carrier tape to the articles by the applicator. Thus is particularly time-consuming and expensive. Thus, only those articles which are of particularly high value such as clothes, compact discs, videos, perfumes, books and spirits tend to be tagged. However, the tags are usually fairly conspicuous and hence can be removed by the thief.
Attempts have been made to provide the articles with tags at source i.e. during the production of the article or during the production of the packaging for the article or at a time when the article is being packaged. These attempts have essentially involved motorising a pressure sensitive adhesive labeller of the above type. However such a system is still expensive because of the need to separate the detectable devices from the carrier tape, wind up the carrier tape from which the detectable devices have been removed, and apply the devices to the articles. Further, the system could, at best, apply 3 or 4 devices per second and hence the article production or article packaging line had to be slowed down with attendant cost disadvantages.
It is an object of the present invention to enable articles to be provided with tags at source automatically, cheaply and rapidly.
According to one aspect of the present invention there is provided a tagging material for the production of a tag for securing to an article to enable the presence of the article to be detected, which tagging material is in the form of a pressure sensitive adhesive tape having a first surface coated with pressure sensitive adhesive composition and a second surface opposite the first surface coated with release agent, the tape including a continuous substrate of synthetic plastics material and a continuous electromagnetic sensor material capable of being detected by detection equipment.
In accordance with one embodiment, the electromagnetic sensor material is adhered to the substrate by the pressure sensitive adhesive composition.
In this case, the electromagnetic sensor material may be in the form of a ribbon having a high magnetic permeability and low coercivity such as Permalloy metal and certain amorphous alloys of iron, nickel or cobalt which, when exposed to a continuous alternating magnetic interrogation field, is driven successively into and out of magnetic saturation by the alternating magnetic interrogation field. This results in a disturbance of the interrogation field such that other magnetic fields are produced at frequencies harmonically related to the interrogation field. The signal represented by these other fields can then be detected. It is particularly preferred for the material of the ribbon to be such that it can be activated so that it reacts in the above way when subjected to such an alternating magnetic interrogation field and then be subsequently deactivated so as not to react in that way. Switchable materials of this type are well known in the art and are described in, for example, U.S. Pat. No. 5,029,291, U.S. Pat. No. 5,121,103, U.S. Pat. No. 5,206,626, U.S. Pat. No. 5,304,983 and U.S. Pat. No. 5,126,270 and also in an article by K H Shin, C D Graham Jr. and P Y Zhou entitled Asymmetric Hysteresis Loops in Cobalt-based Ferromagnetic Alloys at page 2772 of IEEE Transactions on Magnetics, September 1992 (all of which are incorporated herein by reference).
In an alternative embodiment, the electromagnetic sensor material may be of the type incorporating thin film technology. For example, the sensor material may comprise a thin continuous metal film and a perforate metal film adhered to either side of a film of synthetic plastics material. The perforate metal film is then laminated to one face of the substrate, the release agent is coated on the opposite face of the substrate and the pressure sensitive adhesive composition is coated on the continuous metal film. Such materials are, for example, marketed by Esselte Meto. As in the previous embodiment, the electromagnetic sensor material includes Permalloy or amorphous metal alloys.
The substrate of the pressure sensitive adhesive tape will ordinarily be in the form of a thin base film of synthetic plastics material having a thickness of, for example, from 30 to 60 microns and a width of from 2 to 10 mm and preferably not less than 4 mm. The plastics material of the base film is generally oriented either monoaxially or biaxially and any thermoplastic plastics material may be used for the base film provided that it has adequate strength and dimensional stability. Preferably, the base film is formed of monoaxially oriented polypropylene or polyester.
Any suitable pressure sensitive adhesive composition may be used. Thus, it may, for example, be based on natural or synthetic rubber or on acrylic copolymers. Preferably the adhesive is a natural rubber resin solvent based system although aqueous or solvent based acrylic copolymers can be used.
Normally a primer coating is provided between the pressure sensitive adhesive composition and the surface of the base film so as to promote anchorage of the pressure sensitive adhesive composition. That surface of the base film which is not coated with the pressure sensitive composition is generally coated with a release agent such as a silicone release lacquer.
The tagging material of the first aspect of the invention may be produced by coating one of the surfaces of a web of the base film material with the pressure sensitive adhesive composition and the other of its surfaces with the release agent. The coated web is then slit longitudinally into wide strips in a first cutting stage and the strips are then slit longitudinally into narrow tapes in a second cutting stage. A plurality of spaced apart cutting edges is used at each cutting stage. Ribbons of the electromagnetic sensor material are fed to each of the wide strips as it is being cut at the second cutting stage so that a ribbon passes between each pair of adjacent cutting edges and is then effectively adhered to the resultant tapes by means of the pressure sensitive adhesive composition of the tapes. The tape is of a sufficient width that the ribbon does not cover all of the pressure sensitive adhesive composition so that sufficient adhesive surface is available to enable the tape to be wound up onto a reel and to be adhered to the article.
The tagging material can be traverse wound onto a reel in lengths of from 1,000 to 50,000 linear metres, preferably 25,000 metres. The material can be self-wound in that there is no need to include a release paper when winding the material onto a reel.
According to a second aspect of the present invention there is provided a method of providing an article with a means of enabling the presence of the article to be detected which method comprises the steps of:
(i) providing a tagging material as hereinbefore defined,
(ii) causing an article to move along an article path,
(iii) moving the tagging material along a tagging material path converging with the article path,
(iv) severing a predetermined length from the tagging material to form a tag, and
(v) adhering the tag to the article by means of the pressure sensitive adhesive composition.
When applying a tag to an article in accordance with this aspect of the invention, the article may be the product itself in which case the tag is directly applied to the product or the article may be packaging for the product in which case the article is applied to, or incorporated in, the packaging material. In any event, it is preferable that the tag is located such that it is not readily visible since otherwise it could be removed by the thief prior to reaching the point of sale. Thus, for example, the tag may be applied directly to the product and then be covered over by a label so that the tag cannot be seen. Alternatively, the tag can be applied to the back of the label before the label is applied to the product. In alternative embodiments, the tag may be incorporated in a carton in which the product is to be packaged for example in the side seam or the crash lock of the carton or the tag may be sandwiched between the two sheets which are normally laminated together to form the base board of blister packs.
In the case where the article to which the tag is to be applied is a discrete article, then a plurality of the articles may be moved along the article path so that each article receives a tag. Alternatively, if the article is a continuous web of packaging material, then a plurality of tags will be applied to the moving web at locations which are predetermined so that they are not impaired during subsequent cutting or folding operations.
By means of the method of the present invention, it is possible to apply tags to products as they are being produced in the production line or as they are being packaged in the packaging line at a rate of up to 20 tags per second. Thus the production line or packaging line can continue to operate at high speed.
Generally, the tag will be in its deactivated form when applied to the article at source during product manufacture or packaging. Then, a plurality of such tagged articles may be placed on a pallet for transfer to the retail store. All the tags can then be bulk activated simultaneously as they are being supplied into the warehouse of the retail store having the necessary detection equipment so that the articles in the store are activated. Then, at the point of sale, the tag is deactivated so that it will not actuate the detection equipment located between the point of sale and the exit.
According to a third aspect of the present invention there is provided a means of applying a tag to an article which applying means comprises a means for feeding tagging material as hereinbefore defined to an applicator head and a means of feeding an article to said applicator head, wherein said applicator head comprises a detector for detecting the position of an article at the head; a means of severing, from the tagging material, a predetermined length to form a tag; and means for adhering the tag to the article by means of the pressure sensitive adhesive composition of the tag.
In a preferred embodiment of this third aspect of the present invention, the means for feeding the tagging material to the applicator head may be a dispenser of the type described in our European patent No. 0121371 for applying pressure sensitive adhesive tear tape to filmic packaging material (incorporated herein by reference).
The applicator head may comprise a means for feeding the tagging material towards a tag-applying roller which, when the article to be tagged is sensed to be in an appropriate position, causes an incremental encoder to actuate the tagging material feed means to such an extent that a predetermined and controlled length of the tagging material is fed towards the tag-applying roller and is then severed from the remainder of the tagging material to form the tag. As the tag is cut from the tagging material, it is applied to the article by being passed between the article and the tag-applying roller.
The severing means may be in the form of a guillotine or, more preferably, in the form of a rotary cutter including one or more cutting edges.
The tagging material feed means may be in the form of a pair of feed rollers. Preferably, however, the tagging material feed means includes a transport belt co-operating with a shoe or with another transport belt. In this case, the means of severing the tag from the tagging material is preferably a rotary cutter which may be linked to the transport belt so as to operate at the same speed or which may be driven by a separate motor controlled by an incremental encoder so that the length of tag cut from the tagging material can be varied.
In the case where the applicator head includes tagging material feed rollers, the applicator head may include a chamber through which the tagging material passes and positioned between the feed rollers and the tag-applying roller. A current of air is blown through the chamber so as to control the position of the free end of the tagging material after the tag has been cut from it.
The Following Example Illustrates the Invention
A web of monoaxially oriented polypropylene film having a thickness of about 40 xcexcm was formed in conventional manner. One surface of the web was then coated with a release agent comprising 100 parts of Silcolease 425 (a 30% solids concentration of dimethyl polysiloxane and methyl hydrogen polysiloxane resins in toluene from Rhone Poulenc) together with 4 parts of Catalyst 62A and 4 parts of Catalyst 62B (50% solids concentration of aminoalkoxy-polysiloxane in toluene and alkyl tin acrylate in xylene, respectively from Rhone Poulenc). It was applied to give a dry coating weight of 0.25 g/m2.
The other surface of the web was then coated with a primer and a transparent pressure sensitive adhesive composition. The primer was a solution in toluene of 25 parts of natural crepe rubber and 8 parts of a cross-linking agent (Vulcabond TX) to give a coating weight of 0.25 gms per square metre. Vulcabond TX is manufactured by ICI and is a 50% solution of polyisocyanate (mainly diphenyl methane di-isocyanate) in xylene. The pressure sensitive adhesive composition was a solution of 100 parts natural crepe rubber, 110 parts of a tackifying resin having a melting point of 110/115xc2x0 C. (Arkon P) and one part of an oxidant (Irganox) dissolved in a hydrocarbon mixture (SBP2). This was applied by a conventional reverse role coating technique to give a dry coating weight of 15 to 40 g/m2. Arkon P is marketed by Arakara Chemicals and is a fully saturated cyclic hydrocarbon resin and Irganox is marketed by Ciba-Geigy and is a high molecular weight bonded polyphenol.
The thus coated web was then slit longitudinally into strips and each strip was then slit longitudinally so as to provide a plurality of pressure sensitive tapes of width 6 mm.
Amorphous ribbons of Co70.5Fe4.5Si10B15 alloy were prepared by melt spinning in air followed by annealing for about 20 hours at a temperature of 380xc2x0 C. in an applied magnetic field of about 0.3 Oersteds directed parallel to the ribbon axis. As a consequence, an antiferromagnetic film was formed on the alloy substrate which was magnetically exchange coupled with the substrate. The resultant ribbons exhibited asymmetrical hysteresis characteristics and responded to applied interrogation fields by producing narrow high amplitude pulses which were easily detectable.
The ribbons were about 1.2 mm wide and 40 xcexcm thick and were adhered to the middle of the adhesive coated surfaces of the tapes as they were being formed from the strips to form tagging material comprising a continuous length of tape having adhered thereto a continuous length of electromagnetic sensor material. The tagging material was then traverse wound onto cores to provide reels carrying continuous lengths of tagging material of about 25,000 metres long.